The present invention relates to an improved prophylactic sheath or condom of the type normally employed by men to prevent the transmission of venereal diseases and more particularly to pevent the release of semen into the vagina of a woman during interrcourse,
An object of the invention is to provide means for preventing the spilling of semen from the open end or neck of the condom during movements occurring after ejaculation.
A further object is to prevent the sliding of the neck of the condom on the skin of the penis and the untimely slipping of the condom from the penis due to the lubrication resulting from the forcing of the seminal fluid along the surface of the penis under the condom wall by movements occurring during and after ejaculation,
A further object is to prevent or reduce the likelihood of rupturing the condom as sometimes occurs after ejaculation when the relatively dryer external lips of the vagina resists reentry while the male organ, lubricated with semen or precoital fluid, slides freely inside the condom thereby stretching it beyond its elastic limit on a subsequent deep penetration.
It is well known that the thin rubber tubular sheath type of condom occasionally ruptures during coitus. This usually happens during the height of coital movement after ejaculation. The reason for rupture according to some current advertising literature has been attributed to the stretching of the rubber material due to the added volume of the seminal fluid issued from penis. New shapes of such prophylactics now being sold are formed with a small reservoir at the forward end advertised to receive fluid without stretching the condom member itself. These forms with the reservoir are no less likely to rupture than the more conventional form with the simple rounded end, and in fact, under the usual conditions existing after ejaculation the reservoir design is the more likely to rupture. The reasons for this seeming paradox are simple.
The conventional rubber condom has an elastic limit orders of magnitude greater than needed to accommodate the increased volume of the ejaculated semen. If this were not so, one size of condom would not be as universally usable as it is, since the variation in the size of the erect human penis is far greater than the 2 to 5 cc of semen normally issued during ejaculation. As a demonstration it can be shown that such a condom may be stretched repeatedly from a relaxed length near 71/2 inches to a length of 48 inches without damage. Further, it may be blown up with air to a size of 8 inches in diameter and over 30 inches long and relaxed repeatedly without rupture. Therefore it is not the small increase in volume due to semen that contributes to the rupture of a condom after ejaculation.
After the emission of semen the pressure of the forward walls of the vagina against the condom transports the semen along the penis toward the open end of the condom and thereby lubricates the penis so that the condom slips more freely on the penis than against the walls of the vagina. This is especially true if the penis is withdrawn totally or to such an extent that the lubricated portion of the penis extends outside the relatively dryer lips of the vagina. The movement of the condom into the vagina is further inhibited occasionally by resistance against pubic hair. During a subsequent deep penetration of the penis, the closed end of the condom can be stretched beyond its elastic limit. A normal thrust can easily exceed the few pounds of force needed to push through and rupture the thin wall of the rubber membrane. The cutting action of the pubic hair may increase the tendency to rupture.
A condom designed to have a small reservoir at the forward end, ostensibly for receiving and holding semen, does not eliminate the action just described and inherently increases the tendency to rupture under that action because the glans of the penis is forced into the reservoir having a diameter much smaller than the penis and so tends to stretch this region more than any other part of the condom.